KR101596494B1 - Electrode Current Collector Comprising Nonconductor for Preventing Internal Short-Circuit - Google Patents

Abstract

The present invention relates to an electrode current collector including a nonconductive material capable of preventing an internal short circuit, and more particularly, to an electrode current collector in which a nonconductive material is inserted into a metal base material.
This nonconductor can serve as a stopper film for suppressing an internal short circuit, and has an effect of suppressing the flow of electric current inside the battery cell during internal short-circuiting and suppressing the occurrence of ignition.

Description

[0001] Electrode Current Collector Comprising Nonconductor for Preventing Internal Short-Circuit [0002]

The present invention relates to an electrode current collector including an insulator which can prevent an internal short circuit.

As technology development and demand for mobile devices are increasing, the demand for secondary batteries as energy sources is rapidly increasing. Among such secondary batteries, lithium secondary batteries having high energy density and voltage, long cycle life and low self- It has been commercialized and widely used.

Among these secondary batteries, there is a demand for a prismatic battery and a pouch type battery which can be applied to products such as cellular phones with a thin thickness in terms of shape, and a lithium ion battery having high energy density, discharge voltage, There is a high demand for secondary batteries such as polymer batteries.

Generally, a secondary battery includes an electrode assembly composed of a cathode, a cathode, and a separator interposed between the anode and the cathode, which is laminated or wrapped in a battery case of an aluminum can or a laminate sheet in a state of being wound and then injected or impregnated with an electrolyte have.

One of the major research tasks in such secondary batteries is to improve safety. For example, a secondary battery can have a high temperature and / or high temperature inside the battery that can be caused by an abnormal operating condition of the battery, such as an internal short circuit, an overcharged condition exceeding an allowable current and voltage, exposure to a high temperature, The explosion of the battery may be caused by high pressure.

Particularly, among these safety problems, due to repetitive charging / discharging and overcharging, the space inside the cathode where excess lithium ions desorbed from the positive electrode can be inserted becomes insufficient, and lithium ions precipitate from the surface of the negative electrode to lithium metal The problem of safety due to an internal short circuit that occurs when the impurities of the metal components mixed in the process of manufacturing the battery are recrystallized and contacted with the anode through the separator is very serious and alternatives for solving such problems have been examined have.

On the other hand, Li (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ is, for example, a cathode active material having improved heat resistance in the past. In order to improve the cycle life of LiNiO ₂ , which is a low-cost and high-capacity material, and to improve the thermal stability at the time of filling, such an active material is added with a part of Ni instead of Co and Al to thereby suppress migration of Ni cations, It is a cathode active material.

However, when such a cathode active material is used as a cathode material of a battery cell, it is vulnerable to an internal short circuit due to low resistance, and thus has stability problems such as ignition explosion. Particularly, in the case of a large-capacity, large-capacity battery cell such as an automobile, explosion force is considerably large when an internal short circuit occurs. Therefore, in order to use the battery as an actual product, solving such a safety problem is urgent.

Therefore, a need exists for a technique capable of solving such a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have confirmed that a desired effect can be achieved when insulators are inserted into the metal substrate as will be described later, It came to the following.

Therefore, the electrode current collector according to the present invention is characterized in that a non-conductive material is inserted into the metal substrate.

That is, in the electrode current collector according to the present invention, when the non-conducting material is inserted into the metal substrate, the electrode current collector can serve as a stopper film for preventing internal short circuit due to penetration of the external metallic material, The flow of the current in the cell is weakened and it is possible to suppress the progress of the ignition.

In particular, the non-conductor may be in the form of one or more non-conductive films or one or more non-conductive rods.

In one specific example, the non-conductive film may have a predetermined thickness on the metal substrate in the direction of the facing surface of the electrode collector. Specifically, the non-conductive film may have a thickness of 2 to 10 micrometers or less, more specifically, 2 to 8 micrometers or less.

When the thickness of the nonconductor is less than 2 micrometers, cracking or breakage may easily occur and the blocking film may not be properly performed. When the thickness of the nonconductor is more than 10 micrometers, And the formation of a high resistance, etc., and it can hinder the softness and the like of the metal thin film to adversely affect the coated electrode active material, and it is possible to manufacture a compact battery by increasing the thickness of the whole electrode current collector No, material can be wasted.

In one specific example, the non-conductive film may have a width equal to or less than the width of the metal substrate, specifically, the width of the non-conductive film may be 50% or more to 100% or less of the width of the metal substrate, %, The non-conductive film can not have a sufficient width to prevent the flow of current in the battery cell, and the ignition can not be prevented. When it exceeds 100%, the electrode current collector is difficult to manufacture and the material is wasted .

The diameter of the nonconductive rod may be greater than or equal to 2 micrometers and less than or equal to 10 micrometers.

The nonconductive material may be composed of one or more materials selected from the group consisting of rubber, glass, silicone rubber, polyethylene, polyvinyl chloride, polyester, epoxy resin, melamine resin, phenol resin and polyurethane. The rubber may be natural rubber or synthetic rubber. Specifically, the synthetic rubber may be a silicone rubber.

In one specific example, the nonconductor may be composed of a hydrocarbon or may be a bead coated with a thermoplastic resin. The beads coated with the thermoplastic resin can form a close inner layer while melting the thermoplastic resin in the electrode current collector when the temperature inside the battery rises due to an internal short circuit, a nonconductive polymer coating is formed on the conductive material which can be a pass, so that the current flow inside the battery cell can be effectively weakened.

The metal substrate may be made of aluminum (Al), copper (Cu), iron (including stainless steel), or the like.

The thickness of the metal substrate may range from 5 micrometers or more to 20 micrometers or less in the range where the non-conductive material can be inserted into the non-conductive material. The range of the thickness of the metal base is a range applied in an actual battery manufacturing process. At this time, if the thickness of the metal substrate is less than 5 micrometers, the thickness of the current collector is too thin, so that the conductor layer except for the conductor layer is formed too thin and sufficient electron passing may not be achieved.

Specifically, when the metal substrate is made of Al, the thickness may be 10 micrometers or more to 20 micrometers or less. When the metal substrate is Cu, the thickness may be 5 micrometers or more to 20 micrometers or less .

In one specific example, the nonconductor can be inserted into the metal substrate by welding, attachment, or insert injection molding. However, the present invention is not limited to these methods, but can be formed in various ways.

The present invention also provides an electrode coated with an electrode active material or an electrode active material containing an electrode active material on the electrode current collector. The electrode may be a positive electrode or a negative electrode, and the positive electrode may include a lithium transition metal oxide represented by the following Formula 1 or 2 as a positive electrode active material.

Li _x M _y Mn _{2 - y} O _{4 - z z} (1)

In this formula,

M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;

A is one or more anions of -1 or -2;

0.9? X? 1.2, 0 <y <2, 0? Z <0.2.

(1-x) LiM'O _2-y A _y -xLi ₂ MnO _{3 -y '} A _y' (2)

In this formula,

M 'is Mn _a M _b ;

M is one or more selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and two period transition metals;

A is at least one selected from the group consisting of anions of PO ₄ , BO ₃ , CO ₃ , F and NO ₃ ;

0 <x <1, 0 <y? 0.02, 0 <y? 0.02, 0.5? A? 1.0, 0 b? 0.5, a + b =

In one specific example, when the electrode is a cathode, the cathode may include a carbon-based material and / or Si as an anode active material.

The present invention can also be a secondary battery including the electrode.

The secondary battery may be a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery.

The present invention provides a battery module including the secondary battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, the device may be an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for power storage.

Generally, the positive electrode is prepared by applying an electrode mixture, which is a mixture of a positive electrode active material, a conductive material and a binder, on a positive electrode collector, followed by drying. If necessary, a filler may be further added to the mixture.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals, in addition to the lithium transition metal oxide represented by Formula 1 or 2. Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _2-x O ₄ ; LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like, but is not limited thereto.

The cathode current collector generally has a thickness of not less than 3 micrometers and not more than 500 micrometers. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The conductive material is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

On the other hand, the graphite-based material having elasticity may be used as a conductive material, and may be used together with the materials.

The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The lithium secondary batteries generally include an anode, a cathode, a separator interposed between the anode and the cathode, and a non-aqueous electrolyte containing a lithium salt. Other components of the lithium secondary battery will be described below.

The negative electrode is prepared by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 &lt; x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, And Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide and the like can be used, and in particular, a carbon-based material and / or Si can be included.

The negative electrode collector is generally made to have a thickness of not less than 3 micrometers and not more than 500 micrometers. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally not less than 0.01 micrometer to 10 micrometers, and the thickness is generally not less than 5 micrometers and not more than 300 micrometers. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The lithium salt-containing nonaqueous electrolyte is composed of a nonaqueous electrolyte and lithium. Nonaqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like are used as the nonaqueous electrolyte, but the present invention is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

The lithium salt-containing non-aqueous electrolyte may further contain, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. May be added. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In one specific _{example, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of And then adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing non-aqueous electrolyte.

The present invention provides a battery module including the secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, specific examples of the device include a power tool that is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

As described above, since the electrode current collector according to the present invention has a nonconductor inserted in the metal substrate, the electrode current collector can serve as a stopper film for suppressing an internal short circuit due to penetration of external metal material, The flow of current in the battery cell is weakened due to the influence of the time-nonconductive material, thereby suppressing the occurrence of ignition.

1 is a schematic view of an electrode current collector in which a nonconductor is inserted into a metal substrate according to an embodiment of the present invention;
2 is a schematic plan view of an electrode current collector according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the scope of the present invention is not limited thereto.

FIG. 1 is a schematic view of an electrode current collector 100 in which a nonconductor is inserted in a metal substrate according to an embodiment of the present invention. FIG. 2 is a schematic view of an electrode current collector 100 according to an embodiment of the present invention. Is schematically shown.

Referring to FIGS. 1 and 2, a non-conductive material 120 is formed on the electrode current collector 100 in the metal substrate 110 to have a thickness A of not less than 2 micrometers and not more than 10 micrometers, And is inserted in a film form to form an inner layer. In addition, the thickness of the metal substrate is formed to be a thickness (B) of not less than 5 micrometers and not more than 20 micrometers so that the non-conductive material can be inserted therein.

The width of the non-conductor film 120 on the plane is in a range of 50% or more to 100% or less of the width of the flat surface of the metal substrate 110.

That is, in the electrode current collector according to the present invention, the non-conductive material 120 is inserted into the metal substrate, so that the electrode current collector can serve as a stopper film for preventing an internal short circuit due to intrusion of an external metal material, It is possible to suppress the flow of the current in the battery cell to weaken the nonconductor 120 and to prevent the igniter from proceeding.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (20)

And a non-conductor is inserted into the inside of the metal substrate. The electrode collector of claim 1, wherein the non-conductive material is in the form of one or more non-conductive films or one or more non-conductive rods. The electrode collector according to claim 2, wherein the non-conductive film has a thickness of not less than 2 micrometers and not more than 10 micrometers. The electrode collector according to claim 2, wherein the width of the non-conductive film is 50% or more to 100% or less of the width of the metal substrate. The electrode collector according to claim 2, wherein a diameter of the nonconductive rod is not less than 2 micrometers and not more than 10 micrometers. The nonaqueous electrolyte secondary battery according to claim 1, wherein the nonconductor is made of at least one material selected from the group consisting of rubber, glass, silicone rubber, polyethylene, polyvinyl chloride, polyester, epoxy resin, melamine resin, phenol resin, polyurethane Electrode collector. The electrode collector according to claim 6, wherein the rubber is natural rubber or synthetic rubber. The electrode collector according to claim 7, wherein the synthetic rubber is a silicone rubber. The electrode collector according to claim 1, wherein the metal substrate is made of aluminum (Al) or copper (Cu). The electrode collector according to claim 1, wherein the thickness of the metal base is in a range of 5 micrometers or more to 20 micrometers or less in a range in which the non-conductive material can be inserted therein. An electrode comprising an electrode current collector according to any one of claims 1 to 10 applied with an electrode active material or an electrode active material containing an electrode active material. The electrode according to claim 11, wherein the electrode is an anode or a cathode. 13. The electrode according to claim 12, wherein the anode comprises a lithium transition metal oxide represented by the following general formula (1) or (2) as a cathode active material:
Li _x M _y Mn _{2 - y} O _{4 - z z} (1)
In this formula,
M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;
A is one or more anions of -1 or -2;
0.9? X? 1.2, 0 <y <2, 0? Z <0.2.


(1-x) LiM'O _2-y A _y -xLi ₂ MnO _{3 -y '} A _y' (2)
In this formula,
M 'is Mn _a M _b ;
M is one or more selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and two period transition metals;
A is at least one selected from the group consisting of anions of PO ₄ , BO ₃ , CO ₃ , F and NO ₃ ;
0 <x <1, 0 <y? 0.02, 0 <y? 0.02, 0.5? A? 1.0, 0 b? 0.5, a + b = 13. The electrode according to claim 12, wherein the negative electrode comprises a carbon-based material, Si, or a carbon-based material and Si as an anode active material. A secondary battery comprising an electrode according to claim 11. 16. The secondary battery according to claim 15, wherein the secondary battery is a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery. A battery module comprising a secondary battery according to claim 15 as a unit cell. A battery pack comprising the battery module according to claim 17. The device according to claim 18, comprising the battery pack as a power source. 20. The device of claim 19, wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for power storage.

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